Magnetization behavior and magnetoimpedance effect in melt-spun Fe75-xCoxZr8Nb2B15 (x = 5, 10, 15) alloys

Soft magnetic properties of melt-spuned (Fe-Co)-Zr alloy system call be achieved upon suitable partial nanocrystallization by proper thermal treatment. In this study, we have measured the spin-wave stiffness constant, magnetoimpedance and incremental permeability ratio (PR) of Fe25-xCoxZr8Nb2B15 (x = 5. 10, 15) alloys to investigate the influence of the structural changes in the nanocrystallization process as well as the changes of the magnetic properties as a function of annealing temperatures. With increasing Co content, the spin wave stiffness constant and Curie temperature increase. The full-width at half-maximum in the longitudinal PR curves do not change very much for the samples annealed at various temperatures regardless of the presence of magnetic field during the heat treatment. The broadening Nil ratio curves along with increment of frequency may arise from the Circumferential permeability, which is somewhat different from the longitudinal permeability. (C) 2002 Elsevier Science B.V. All rights reserved.